It is often desirable to track the location of animals for scientific, personal, or environmental reasons. In particular, pet owners, such as dog owners, are interested in tracking the location of their pets to ensure that they do not get lost or otherwise harmed. For example, hunting dogs are often equipped with tracking devices to locate the dogs in case the dogs become lost during hunting or training. Conventional dog location systems use various means for providing information related to the dog's location back to the user.
In basic dog tracking systems, the dog is typically equipped with a transmitter which periodically sends out a radio ping. The user is equipped with a radio receiver capable of picking-up this ping. In such systems, the receiver is designed so that the signal strength of the received radio signal is directly related to a sound generated by the user's receiver. A strong radio signal would produce a loud audible sound, and conversely, a weak radio signal would produce a faint sound. By determining the direction of the loudest sound, that same direction could be used to track the dog.
Later systems began to take advantage of Global Positioning System (GPS) technology. In these GPS animal tracking systems, the dog is equipped with a GPS receiver and a radio link back to the user. The GPS receiver provides the global longitude and latitude of the dog's location and the radio link transmits this data back to the user. The user would have a radio receiver to capture the data signal to provide the global location of the dog. This longitude and latitude data could then be transposed onto a topographical map which would provide the heading necessary to track the dog.
As these GPS animal tracking systems became more affordable and compact, modern GPS dog tracking systems began to incorporate a second GPS receiver in the user's radio receiver. This second GPS receiver enables the user to display the relative position and distance of the dog in relation to the user's current position. This information can be provided to the user in numeric form or in more intuitive graphical formats.